Polyglycerol compounds are well known materials. They are made by the condensation reaction of glycerin. The resulting products are polar and posses several un-reacted hydroxyl groups. The number of glycerin molecules condensed in the reaction is referred to as the degree of polymerization (DP). The condensation reaction run between two glycerin molecules produces water as a byproduct. U.S. Pat. No. 5,721,305 issued Feb. 24, 1998 to Eshuis, et al. entitled Polyglycerol production teaches how polyglycerol is made.
U.S. Pat. No. 3,936,391 issued Feb. 3, 1976 to Gabby entitled “Hydrated polyglycerol Ester Composition” teaches a polyglycerol ester emulsifier is prepared by heating a polyglycerol ester containing 3 to 10 glycerol units and a 1 to 2 saturated fatty acyl ester groups containing 16 to 20 carbon atoms, glycerol and water at a temperature of 125 to 135° F. The heat is maintained until a homogeneous paste-like consistency is imparted thereto.
U.S. Pat. No. 5,674,475 issued Oct. 7, 1997 to Dahms entitled “Emulsifier Composition based on Polyglycerol Ester” teaches an emulsifier composition of a mixture of polyglycerol fatty acid esters and the lactylate of a fatty acid or its salt. This emulsifier is used to manufacture a wide range of different oil in water emulsions.
U.S. Pat. No. 1,424,137 issued July 1922 to Weisberg, entitled “Polyglycerol Resins” discloses a polyglycerol ester of an aromatic dibasic acid used in shellac. This patent, imported herein by reference, addresses solid resins made in solvent. While lacking the critical control of cross-linking and producing a hard rather than a soft ester, this patent shows the state of the art in resins.
Still another U.S. Pat. No. 7,638,116, issued Dec. 29, 2009 by LaVay et al. entitled “Polyglycerol dimer polyester resins” discloses a polyglycerol dimer resin of a polyglycerol containing 3 to 10 repeat units cross-linked by dimer acid. While lacking the critical control of cross-linking and functionalization by fatty groups, this patent shows the state of the art of polyglycerol dimer polyesters.
UVA protection has been a source of increasing discussion worldwide due to the steadily climbing rates of skin cancer, and particularly malignant melanoma. There have been many who say one of the problems has been the emphasis on SPF, which have steadily increased, and not enough emphasis on UVA protection. The SPF test is a measurement of erythema and 85% to 90% of the erytema energy is UVB energy. While this means that to obtain SPFs higher than 10, some UVA protection must be present the SPF test provides little indication of the magnitude of the UVA protection. In fact, based on the 2007 FDA Sunscreen Monograph, Sunscreen Drug Products for Over-the-Counter Human Use; Proposed Amendment of Final Monograph; Proposed Rule, (2007 Monograph) the instruments utilized to test SPF may have as little as 9% of the erythemal energy coming from UVA and as little as 3% of the erythemal energy coming from UVAI energy. UVA energy is defined as the Ultraviolet energy from 320 nm to 400 nm and UVAI energy is defined as energy from 340 nm to 400 nm. There are several UVA tests that exist worldwide, but only since the 2007 Monograph has there been anything official in the US. The 2007 monograph lists two UVA tests that must be performed. One test, the JCIA Persistent Pigment Darkening test compares the amount of energy needed to produce melagenesis(tan) in unprotected skin versus the amount of energy needed to produce a tan in protected skin. This test predominantly is based on the amount of UV energy absorbed in the UVAII, 320 nm to 340 nm area of the Ultraviolet spectra. The FDA recognizing this devised a second test to measure the energy absorbed in the UVAI area of the spectra. Simply stated, this in vitro test is based on dividing the average amount of absorbance in the UVAI area by the average amount of absorbance in the entire UV spectra.
The resultant ratio determines the amount of UVA protection that can be labeled. Front panel labeling is required to reflect this by a star system and descriptor system as follows:
UVAI/UV RatioDescriptorNo. of Stars<20No UVA claim0.20-.39Low UVA1.40-.69Medium2.70-.95High3>0.95Highest4
To obtain the desired ratio, product absorbance must have increasing magnitude of absorbance in the UVA region and increasing breadth in the longer UVAI wavelengths. To obtain the highest rating the product needs to absorb as much in the long UVAI wavelengths as is absorbed in the shorter wavelengths. While this sounds simple in theory, it is very contradictory to common sunscreen products in the US as well as the world, which almost always have the predominant amount of their absorbance in the UVB region and then rapidly taper off in the UVAII and UVAI. Obtaining the highest ratio with an SPF of 30 or higher is practically impossible with existing US approved sunscreen active materials without using a product so opaque that few if any would use.
The only chemical sunscreen available to use in the US that absorbs with any significance in the UVAI region is Butyl Methoxydibenzoylmethane, more commonly known as Avobenzone. And even Avobenzone is woefully lacking in producing the broad coverage needed to obtain a 4 star, high SPF product since the maximum absorbance of Avobenzone in a polar solvent such as ethanol is 357 nm and the absorbance drops off extremely fast at increasingly higher wavelengths. The maximum absorbance is even lower in non-polar solvents such as most oils. This situation is exacerbated by the fact that once an alcohol product is applied to the skin the alcohol quickly evaporates leaving the Avobenzone in an increasingly polar environment. Further to that most sunscreen products are in fact emulsions that have the Avobenzone dissolved in a non-polar oil phase in order for it to be solubilized and emulsified. The maximum absorbance in some commonly used oil ingredients used to solubilize and emulsify Avobenzone have in fact much lower maximum absorptions. For example Avobenzone maximum absorbance in Mineral Oil is only at at 351 nm and C12-15 Alkyls Benzoate is at 355 nm. Note a typical absorption pattern for Avobenzone in C12-15 alkyl benzoate, run using a UV-Visible spectrophotometer results in a spectrum with very little absobance in the range of 390 nm. Improving the absorbance at this wavelength would result in an improved star rating.
It is known in the art that light radiation of wavelengths of from 290 to 320 nm, i.e., UV-B irradiation, causes skin burning and erythema. For these reasons, as well as for aesthetic reasons, there is an increasing demand for means of controlling this natural tanning in order to thereby control the color of the skin. This UV-B radiation must thus be screened from the skin.”
It is also known to this art that UV-A radiation, of wavelengths of from 320 to 400 nm, which tan the skin, also adversely affects it, especially in the case of sensitive skin or skin which is continually exposed to solar radiation. UV-A rays especially cause a loss in the elasticity of the skin and the appearance of wrinkles, promoting premature skin aging. Such irradiation promotes triggering of the erythemal reaction or amplifies this reaction in certain individuals and may even be the source of phototoxic or photoallergic reactions. Thus, for aesthetic and cosmetic reasons, such as conservation of the natural elasticity of the skin, for example, an ever-increasing number of individuals wish to control the effect of UV-A rays on their skin, it is desirable to also screen out UV-A radiation.
A wide variety of compounds suited for photoprotection (UV-A and/or UV-B) of the skin are known to this art. Most of these are aromatic compounds exhibiting absorption of UV radiation in the region from 280 to 315 nm, or in the region from 315 to 400 nm, or in both of these regions. There is no good way known at present to modify the absorption properties of molecules to meet the specific needs, or to combine products to cover a wide range of UV wavelengths. Products heretofore known are typically formulated into antisun or sunscreen compositions which are in the form of an emulsion of oil-in-water type or water in oil type, and which thus contain, in various concentrations, one or more conventional lipophilic and/or hydrophilic organic screening agents. These are capable of selectively absorbing harmful UV radiation of specific wavelength, depending upon structure of such screening agents (and their amounts) being selected as a function of the desired sun protection factor SPF (the sun protection factor being expressed mathematically by the ratio of the irradiation time required to attain the erythema-forming threshold with the UV screening agent to the time required to attain the erythema-forming threshold in the absence of UV screening agent).
It is a long felt need to have a sunscreening agent that can absorb ultra violet radiation at specific desired wavelengths. In addition, these compounds exhibiting anti-UV activity must also have good cosmetic properties in compositions comprised thereof, good solubility in the usual solvents, and in particular fatty substances such as oils and greases, as well as good resistance to water and to perspiration.
None of the references above understood the desirability of incorporation of fatty groups incorporated onto a polyglycerol backbone to produce an unknown polymer that acts synergistically to improve sunscreening performance.